The present invention relates to electronic equipment provided with a microprocessor, such as a video tape recorder and the like apparatuses.
In the past, most of electronic equipment have been such that various kinds of control are executed according to a program written in a microprocessor and a read-only memory unit.
FIG. 5 shows an example of the electronic equipment of the prior art.
A read-only memory unit 51 (hereinafter simply referred to as ROM 51) stores a program for operating a central processing unit 53 (hereinafter simply referred to as CPU 53). A random-access memory unit 52 (hereinafter simply referred to as RAM 52) is stored with a ROM correction data (hereinafter referred to as RCD) consisting of the following:
(1) a program for correcting the program stored in the ROM 51;
(2) a point of correction, which is a locative information of a point for initiating an execution of the correction program; and
(3) a version number of the correction program.
The CPU 53 executes the correction program stored in the RAM 52 when it reaches the point of correction (hereinafter simply referred to as correcting point), which is the locative information of a point for initiating an execution of the correction program in the RAM 52, while also executing the program stored in the ROM 51. An internal nonvolatile memory 54 (hereinafter simply referred to as memory 54) stores the RCD, and transfers the RCD to the RAM 52 according to a command of the CPU 53.
The electronic equipment of the prior art constructed as foregoing operates in a manner which will be described hereinafter.
Initially, the RCD is not stored in the memory 54. If the RCD is stored in the memory 54 under the above circumstance, the ROM 51 shall have a program in advance for proceeding with transferring the data to the RAM 52 in time with a resetting of the CPU 53. Since the RCD is not stored in the memory 54 in the case of the present example, no RCD is present for being transferred to the RAM 52. Therefore, the CPU 53 operates only in accordance with the program stored in the ROM 51.
In case if any problem is found in the program stored in the ROM 51 after the electronic equipment is completed, the memory 54 is replaced with another nonvolatile memory stored with an RCD for correcting the problem. Hence, the CPU53 transfers the RCD stored in the replaced memory 54 to the RAM 52 in time with a resetting of the CPU 53. Therefore the CPU 53 executes the program in the ROM 51. The CPU 53 also executes the correction program in the RAM 52, when it reaches a correcting point stored in the RAM 52. In this way, the problem in the program stored in the ROM 51 can be corrected.
Generally, the ROM 51 has a larger memory, and takes a longer lead-time as compared to the memory 54. Therefore, it is more expedient both in cost and time to replace the memory 54 than the ROM 51. Also, the removed memory 54 can be reused again, since it is rewritable (thereby reducing the cost).
In the foregoing electronic equipment of the prior art, however, it is necessary that the equipment be disassembled for replacement of a component in order to correct the program stored in the ROM 51. It has been a problem of costing much labor for the above reason.
The present invention is intended to avert the above problems, and it aims at providing electronic equipment that can readily make correction of a program stored in a ROM unit without disassembling the equipment.
In order to achieve this object, electronic equipment of the present invention comprises:
(1) a ROM unit stored with a program for operating a CPU unit;
(2) a RAM unit for storing an RCD, which is composed of a program for correcting the program in the ROM unit, a correcting point, and a version number of the correction program;
(3) a CPU unit for executing the correction program in the RAM unit when it reaches the correcting point stored in the RAM unit, while executing the program of the ROM unit at the same time;
(4) an internal nonvolatile memory for storing the RCD, and transferring the RCD to the RAM unit according to a command of the CPU unit; and
(5) a data transfer unit capable of connecting between an external nonvolatile memory storing the RCD and the internal nonvolatile memory via a connector without requiring disassembly of the electronic equipment.
If any problem is found in the program stored in the ROM unit after the electronic equipment is completed, an RCD for correcting the problem is prepared, and the RCD is stored in the external nonvolatile memory separate from the electronic equipment. The external nonvolatile memory is then connected to the connector equipped in the electronic equipment. The data transfer unit connected with the connector transfers the RCD stored in the external nonvolatile memory to the internal nonvolatile memory, either automatically by detecting the connection with the external nonvolatile memory storing the RCD outside of it, or at a command of the CPU unit. In this way, the electronic equipment of the present invention composed as above can readily update the RCD in the internal nonvolatile memory without disassembling the equipment. The CPU unit is subsequently reset by unplugging and plugging the AC supply plug, or by turning off and on the power supply to the electronic equipment. The CPU unit transfers the RCD stored in the internal nonvolatile memory to the RAM unit by this resetting operation. The CPU unit executes the program in the ROM unit as well as the correction program in the RAM unit, as it reaches the correcting point stored in the RAM unit. The problem of the program stored in the ROM unit can be corrected in this manner.
Accordingly, the electronic equipment of the present invention is able to make a correction of the program stored in the ROM unit easily without disassembling the equipment, as has been required with the prior art equipment.